Forming shaped fiber fabrics

ABSTRACT

A fibrous product including a mixture of different shaped fibers is formed utilizing a spin pack assembly including a spinneret with at least two spinneret orifices having different cross-sections. In addition, the formation of the fibrous product is enhanced by controlling the pressure drop upstream from the spinneret orifices, which in turn facilitates effective control of fiber denier. A metering/distribution plate is preferably provided in the spin pack with channels having selected dimensions that control the pressure drop of molten polymer flowing through the spin pack. The metering/distribution plate can be retrofitted into existing systems and easily exchanged with other metering/distribution plates to enhance formation of the fibrous product with different fiber shapes.

CROSS-REFERENCE TO RELATED APPLICATION

This application claims priority from U.S. Provisional PatentApplication Ser. No. 60/588,328, entitled “Mixed Filament Spunbond” andfiled Jul. 16, 2004. The disclosure of the above-identified patentapplication is incorporated herein by reference in its entirety.

FIELD OF THE INVENTION

The present invention relates to equipment for forming fibrous fabricscomprising a mixture of shaped fibers.

BACKGROUND OF THE INVENTION

Commercial woven and nonwoven fabrics are typically comprised ofsynthetic polymers formed into fibers. These fabrics are typicallyproduced with solid fibers that have a high inherent overall density,typically in the range of from about 0.9 g/cm³ to about 1.4 g/cm³. Theoverall weight or basis weight of the fabric is often dictated by adesired opacity and a set of mechanical properties of the fabric topromote an acceptable thickness, strength, and protection perception.

One reason for the increased usage of polyolefinic polymers, mainlypolypropylene and polyethylene, is that their bulk density issignificantly lower than polyester, polyamide and regenerated cellulosefiber. Polypropylene density is around about 0.9 g/cm³, while theregenerated cellulose and polyester density values can be higher thanabout 1.35 g/cm³. The lower bulk density means that at equivalent basisweight and fiber diameter, more fibers are available to promote athickness, strength and protection perception for the lower densitypolypropylene.

Another method of addressing consumer acceptance by increasing theopacity of a fabric is by reducing the overall fiber diameter or denier.In fabrics, the spread of “microfiber” technology for improved softnessand strength has become fashionable. Other ways to improve opacity andstrength while reducing basis weight and cost at the same time isdesired.

SUMMARY OF THE INVENTION

In accordance with the present invention, a spinneret comprising atleast two spinneret orifices having geometries distinct from each otheris provided to form mixed filament fiber products. The differentspinneret orifices can be provided at any selected ratio, and any typesof cross-sectional fiber geometries can be formed (e.g., multi-lobal,mixed multi-lobal and round of various sizes).

In accordance with another embodiment of the present invention, ametering/distribution plate is provided for use in a spin pack assemblythat comprises a spinneret including a first set of spinneret orificesand a second set of spinneret orifices, the spinneret orifices of thefirst set having geometries distinct from the spinneret orifices of thesecond set. The metering/distribution plate comprises a first set ofpassages configured to deliver molten polymer flowing through the spinpack assembly to the first set of spinneret orifices, and a second setof passages configured to deliver molten polymer flowing through thespin pack assembly to the second set of spinneret orifices. The passagesof the first set may have dimensions that differ from the dimensions ofthe passages of the second set, and the dimensions of the passages foreach set are selected to facilitate the formation of extruded fibersthrough the first and second sets of spinneret orifices having selecteddeniers. The metering/distribution plate decouples the pressure dropfrom the spinneret orifices to facilitate greater control in orificegeometry and fiber denier.

In still another embodiment of the present invention, a spin packassembly comprises a spinneret comprising a first set of spinneretorifices and a second set of spinneret orifices, the spinneret orificesof the first set having geometries distinct from the spinneret orificesof the second set. The spin pack assembly further comprises ametering/distribution plate configured to deliver molten polymer flowingthrough the spin pack assembly to the spinneret, themetering/distribution plate comprising a a first set of passagesconfigured to deliver molten polymer flowing through the spin packassembly to the first set of spinneret orifices, and a second set ofpassages configured to deliver molten polymer flowing through the spinpack assembly to the second set of spinneret orifices. The spin pack isfurther configured to receive different metering/distribution plates,such that one metering/distribution plate can be exchanged for anotherdepending upon a particular application.

The above and still further objects, features and advantages of thepresent invention will become apparent upon consideration of thefollowing detailed description of specific embodiments thereof,particularly when taken in conjunction with the accompanying drawingswherein like reference numerals in the various figures are utilized todesignate like components.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 illustrates a cross-sectional view of a round hollow fiber with ashaped hollow core.

FIG. 2 illustrates a cross-sectional view of a round hollow fiber whichhas a round hollow core.

FIGS. 3A-3D illustrate cross-sectional views of several shaped fibers.

FIGS. 4A-4E illustrate cross-sectional views of several shaped hollowfibers.

FIG. 5A depicts a bottom view in plan of a portion of a spinneret inaccordance with an embodiment of the present invention, in which thequench air direction is shown with arrows and the spinneret includestrilobal and solid round spinneret orifices in a ratio of about 90:10 oftrilobal to round.

FIGS. 5B and 5C depict the orifice configurations for forming solidround and trilobal fibers with the spinneret of FIG. 5A.

FIG. 5D depicts an enlarged view of a portion of the spinneret of FIG.5A.

FIG. 6A depicts a bottom view in plan of a portion of a spinneret inaccordance with another embodiment of the present invention, in whichthe quench air direction is shown with arrows and the spinneret includestrilobal and solid round spinneret orifices in a ratio of about 75:25 oftrilobal to round.

FIG. 6B depicts an enlarged view of a portion of the spinneret of FIG.6A.

FIG. 7A depicts a bottom view in plan of a portion of a spinneret inaccordance with another embodiment of the present invention, in whichthe quench air direction is shown with arrows and the spinneret includestrilobal and solid round spinneret orifices in a ratio of about 50:50 oftrilobal to round.

FIG. 7B depicts an enlarged view of a portion of the spinneret of FIG.7A.

FIG. 8A depicts a bottom view in plan of a portion of a spinneret inaccordance with a further embodiment of the present invention, in whichthe quench air direction is shown with arrows and the spinneret includestrilobal and hollow round spinneret orifices in a ratio of about 50:50of trilobal to round.

FIGS. 8B and 8C depict the orifice configurations for forming hollowround and trilobal fibers with the spinneret of FIG. 8A.

FIG. 8D depicts an enlarged view of a portion of the spinneret of FIG.8A.

FIG. 9A depicts a bottom view in plan of a portion of a spinneret inaccordance with another embodiment of the present invention, in whichthe quench air direction is shown with arrows and the spinneret includestrilobal and solid round spinneret orifices in a ratio of about 75:25 oftrilobal to round, with arrows showing a double sided quench and areverse in trilobal spinneret orifice orientation occurring at oppositelocations about a centerline of the spinneret.

FIG. 9B depicts an enlarged view of a portion of the spinneret of FIG.9A.

FIG. 10A depicts a top view in plan of a portion of a distributionmetering plate that feeds each individual capillary orifice of aspinneret in accordance with the present invention.

FIG. 10B depicts an enlarged view of a portion of the distributionmetering plate of FIG. 10A.

FIG. 11 depicts an exploded view in elevation and partial section of aspin pack assembly in accordance with the present invention includingtwo melt pumps for supplying and regulating molten polymer flow throughthe assembly.

FIG. 12 depicts an exploded view in elevation and partial section of aspin pack assembly in accordance with the present invention including asingle melt pump for supplying molten polymer to the assembly.

FIG. 13 depicts an exploded view in elevation and partial section ofanother spin pack assembly in accordance with the present inventionincluding a single melt pump for supplying molten polymer to theassembly.

FIG. 14A depicts a perspective view of a drilled metering plate for usewith a spin pack assembly in accordance with the present invention.

FIG. 14B depicts an enlarged view of a portion of the metering plate ofFIG. 14A.

FIG. 15 depicts a schematic of an exemplary spunbond systemincorporating a spin pack assembly in accordance with the presentinvention.

FIG. 16 is a graph of the opacity measurement for different shapedfibers.

FIG. 17 is a chart showing the MD-to-CD ratio of different shapedfibers.

FIG. 18 is a graph of the CD tensile strength of different shapedfibers.

DETAILED DESCRIPTION OF THE INVENTION

All percentages, ratios and proportions used herein are by weightpercent of the composition, unless otherwise specified. Examples in thepresent application are listed in parts of the total composition.

The specification contains a detailed description of (1) materials ofthe present invention, (2) configuration of the fibers, (3) distributionof fiber mixtures, (4) material properties of the fibers, (5) equipmentand processes, and (6) articles.

(1) Materials

Thermoplastic polymeric and non-thermoplastic polymeric materials may beused in the present invention. The thermoplastic polymeric material musthave rheological characteristics suitable for melt spinning. Themolecular weight of the polymer must be sufficient to enableentanglement between polymer molecules and yet low enough to be meltspinnable. For melt spinning, thermoplastic polymers having molecularweights below about 1,000,000 g/mol, preferably from about 5,000 g/molto about 750,000 g/mol, more preferably from about 10,000 g/mol to about500,000 g/mol and even more preferably from about 50,000 g/mol to about400,000 g/mol.

The thermoplastic polymeric materials must be able to solidifyrelatively rapidly, preferably under extensional flow, and form athermally stable fiber structure, as typically encountered in knownprocesses such as a spin draw process for staple fibers or a spunbondcontinuous fiber process. Preferred polymeric materials include, but arenot limited to, polypropylene and polypropylene copolymers, polyethyleneand polyethylene copolymers, polyester, polyamide, polyimide, polylacticacid, polyhydroxyalkanoate, polyvinyl alcohol, ethylene vinyl alcohol,polyacrylates, and copolymers thereof and mixtures thereof. Othersuitable polymeric materials include thermoplastic starch compositionsas described in detail in U.S. publications 2003/0109605A1 and2003/0091803. Other suitable polymeric materials include ethyleneacrylic acid, polyolefin carboxylic acid copolymers, and combinationsthereof.

The shaped fibers of the present invention may be comprised of anon-thermoplastic polymeric material. Examples of non-thermoplasticpolymeric materials include, but are not limited to, viscose rayon,lyocell, cotton, wood pulp, regenerated cellulose, and mixtures thereof.The non-thermoplastic polymeric material may be produced via solution orsolvent spinning. The regenerated cellulose is produced by extrusionthrough capillaries into an acid coagulation bath.

Depending upon the specific polymer used, the process, and the final useof the fiber, more than one polymer may be desired. The polymers of thepresent invention are present in an amount to improve the mechanicalproperties of the fiber, improve the processability of the melt, andimprove attenuation of the fiber. The selection and amount of thepolymer will also determine if the fiber is thermally bondable andaffect the softness and texture of the final product. The fibers of thepresent invention may be comprised of a single polymer, a blend ofpolymers, or be multicomponent fibers comprised of more than onepolymer.

Multiconstituent blends may be desired. For example, blends ofpolyethylene and polypropylene (referred to hereafter as polymer alloys)can be mixed and spun using this technique. Another example would beblends of polyesters with different viscosities or termonomer content.Multicomponent fibers can also be produced that contain differentiablechemical species in each component. Non-limiting examples would includea mixture of 25 melt flow rate (MFR) polypropylene with 50MFRpolypropylene and 25MFR homopolymer polypropylene with 25MFR copolymerof polypropylene with ethylene as a comonomer.

Optionally, other ingredients may be incorporated into the spinnablecomposition. The optional materials may be used to modify theprocessability and/or to modify physical properties such as opacity,elasticity, tensile strength, wet strength, and modulus of the finalproduct. Other benefits include, but are not limited to, stability,including oxidative stability, brightness, color, flexibility,resiliency, workability, processing aids, viscosity modifiers, and odorcontrol. Examples of optional materials include, but are not limited to,titanium dioxide, calcium carbonate, colored pigments, and combinationsthereof. Further additives including, but not limited to, inorganicfillers such as the oxides of magnesium, aluminum, silicon, and titaniummay be added as inexpensive fillers or processing aides. Other suitableinorganic materials include, but are not limited to, hydrous magnesiumsilicate, titanium dioxide, calcium carbonate, clay, chalk, boronnitride, limestone, diatomaceous earth, mica glass quartz, and ceramics.Additionally, inorganic salts, including, but not limited to, alkalimetal salts, alkaline earth metal salts and phosphate salts may be used.

(2) Configuration

The fiber shapes in the present invention may consist of solid round,hollow round and various multi-lobal shaped fibers, among other shapes.A mixture of shaped fibers having cross-sectional shapes that aredistinct from one another is defined to be at least two fibers havingcross-sectional shapes that are different enough to be distinguishedwhen examining a cross-sectional view with a scanning electronmicroscope. For example, two fibers could be trilobal shape but onetrilobal having long legs and the other trilobal having short legs.Although not preferred, the shaped fibers could be distinct if one fiberis hollow and another solid even if the overall cross-sectional shape isthe same.

The multi-lobal shaped fibers may be solid or hollow. The multi-lobalfibers are defined as having more than one critical point along theouter surface of the fiber. A critical point is defined as being achange in the absolute value of the slope of a line drawn perpendicularto the surface of fiber when the fiber is cut perpendicular to the fiberaxis. Shaped fibers also include crescent shaped, oval shaped, squareshaped, diamond shaped, or other suitable shapes.

Solid round fibers have been known to the synthetic fiber industry formany years. These fibers have a substantially optically continuousdistribution of matter across the width of the fiber cross section.These fibers may contain microvoids or internal fibrillation but arerecognized as being substantially continuous. There are no criticalpoints for the exterior surface of solid round fibers.

The hollow fibers of the present invention, either round or multi-lobalshaped, will have a hollow region. A solid region of the hollow fibersurrounds the hollow region. The perimeter of the hollow region is alsothe inside perimeter of the solid region. The hollow region may be thesame shape as the hollow fiber or the shape of the hollow region can benon-circular or non-concentric. There may be more than one hollow regionin a fiber.

The hollow region is defined as the part of the fiber that does notcontain any material. It may also be described as the void area or emptyspace. The hollow region will comprise from about 2% to about 60% of thefiber. Preferably, the hollow region will comprise from about 5% toabout 40% of the fiber. More preferably, the hollow region comprisesfrom about 5% to about 30% of the fiber and most preferably from about10% to about 30% of the fiber. The percentages are given for a crosssectional region of the hollow fiber (i.e. two dimensional). Ifdescribed in three dimensional terms, the percent void volume of thefiber will be equivalent to the percent of hollow region.

The percent of hollow region must be controlled for the presentinvention. The percent hollow is preferably not below 2% or the benefitof the hollow region is not significant. However, the hollow region mustnot be greater than 60% or the fiber may collapse. The desired percenthollow depends upon the materials used, the end use of the fiber, andother fiber characteristics and uses.

The fiber “diameter” of the shaped fiber of the present invention isdefined as the circumscribed diameter of the outer perimeter of thefiber. For a hollow fiber, the diameter is not of the hollow region butof the outer edge of the solid region. For a non-round fiber, fibersdiameters are measured using a circle circumscribed around the outermostpoints of the lobes or edges of the non-round fiber. This circumscribedcircle diameter may be referred to as that fiber's effective diameter.Preferably, the fiber will have a diameter of less than 200 micrometers.More preferably the fiber diameter will be from about 3 micrometers toabout 100 micrometers and preferably from about 3 micrometer to about 50micrometers. Fiber diameter is controlled by factors including, but notlimited to, spinning speed, mass throughput, temperature, spinneretgeometry, and blend composition. The term spundlaid diameter refers tofibers having a diameter greater than about 12.5 micrometers. This isdetermined from a denier of greater than about 1.0 dpf. The basis forusing denier in this invention is polypropylene. A 1.0 denierpolypropylene fiber that is solid round with a density of about 0.900g/cm3 has a diameter of 12.55 micrometers. Spunlaid diameters aretypically from about 12.5 to about 200 microns and preferably from about12.5 to about 150 microns. Meltblown diameters are smaller than spunlaiddiameters. Typically, meltblown diameters are from about 0.5 to about12.5 micrometers. Preferable meltblown diameters range from about 1 toabout 10 micrometers.

The average fiber diameter of two or more shaped fibers havingcross-sectional shapes that are distinct from on another is calculatedby measuring each fiber type's average diameter, adding the averagediameters together, and dividing by the total number of fiber types(different shaped fibers). The average fiber denier is also calculatedby measuring each fiber type's average denier, adding the averagedeniers together, and dividing by the total number of fiber types(different shaped fibers). A fiber is considered having a differentdiameter or denier if the average diameter is at least about 10% higheror lower. The two or more shaped fibers having cross-sectional shapesthat are distinct from one another may have the same diameter ordifferent diameters. Additionally, the shaped fibers may have the samedenier or different denier. In some embodiments, the shaped fibers willhave different diameters and the same denier.

The shaped fibers of the present invention will have a lower overallapparent bulk density. The apparent bulk density is less than the actualdensity of the same polymeric composition used for of a solid roundfiber with the same circumscribed diameter. The apparent bulk densitywill be from about 2% to about 50% and preferably from about 5% to about35% less than the actual density. Apparent bulk density, as used herein,is defined as the density of a shaped fiber with a circularcircumscribed diameter as if it were a solid round fiber. The apparentbulk density is less because the mass of the fiber is reduced while thecircumscribed volume remains constant. The mass is proportional to thearea. For example, the apparent bulk density of a tribal fiber is thecircumscribed area of the shaped fiber. Therefore, the apparent bulkdensity is calculated by measuring the total solid area compared to thetotal circumscribed area. Similarly, the apparent bulk density of ahollow round fiber is measured by the total circumscribed area of thefiber minus the area of the hollow region. The apparent bulk density ofthe collection of shaped fibers in a layer can also be calculated.

FIG. 1 illustrates a round hollow fiber. The shape of the hollow regionof this fiber is not round. FIG. 2 is used to illustrate a round hollowfiber. As shown, the center of the hollow region and the center of thehollow fiber are the same. Additionally, the shape or curvature of theperimeter of the hollow region and the hollow fiber are the same. FIGS.3A-3D illustrate several different shapes of the fibers includingvarious trilobal and multi-lobal shapes. FIGS. 4A-4E illustrate shapedhollow fibers.

Multi-lobal fibers include, but are not limited to, the most commonlyencountered versions such as trilobal and delta shaped. Other suitableshapes of multi-lobal fibers include triangular, square, star, orelliptical. These fibers are most accurately described as having atleast one critical point. Multi-lobal fibers in the present inventionwill generally have less than about 50 critical points, and mostpreferably less than about 20 critical points. The multi-lobal fiberscan generally be described as non-circular, and may be either solid orhollow.

The mono and multiconstituent fibers of the present invention may be inmany different configurations. Constituent, as used herein, is definedas meaning the chemical species of matter or the material. Fibers may beof monocomponent in configuration. Component, as used herein, is definedas a separate part of the fiber that has a spatial relationship toanother part of the fiber.

The fibers of the present invention may be multicomponent fibers.Multicomponent fibers, commonly a bicomponent fiber, may be in aside-by-side, sheath-core, segmented pie, ribbon, or islands-in-the-seaconfigurations. Alternativel, the multicomponent fibers may be mixedhomo or single component fibers. The sheath may be non-continuous orcontinuous around the core. If present, a hollow region in the fiber maybe singular in number or multiple. The hollow region may be produced bythe spinneret design or possibly by dissolving out a water-solublecomponent, such as PVOH, EVOH and starch, for non-limiting examples.

(3) Distribution of Fiber Mixtures

The fiber shapes in the present invention are mixed together in a singlelayer to provide a synergistic effect versus the presence ofsubstantially all round fibers alone or substantially all non-roundfibers alone. “Substantially all” is defined as having less than about5% of different shapes and is not intended to exclude layers whereinless than 5% of the fibers are different due to not being able tocompletely control the process. The mixture of shaped fibers havingcross-sectional shapes that are distinct from one another in a singlelayers is also more beneficial that a nonwoven with discrete layers offibers having distinct cross-sectional shapes. For example, the fibrousfabric of the present invention may perform differently and be moredesired than a nonwoven laminate where one distinct layer hassubstantially all solid round fibers and another distinct layer hassubstantially all trilobal fibers. These benefits may be observed inopacity and/or mechanical properties. It is believed that the mixture ofshaped fibers in a single layer may be beneficial because the differentshapes may prevent roping or other non-uniformity issues duringproduction.

Due to the need to control fabric opacity and mechanical properties,numerous combinations of fibers shapes mixed together are possible. Ingeneral, the fiber mixtures will comprise solid round and hollow round,solid round and multi-lobal, hollow round and multi-lobal, and solidround and hollow round and multi-lobal and combinations thereof.

In order to manifest the additional benefits of fiber mixtures, theminor component of the mixture must be present in sufficient amount toenable differentiation versus 100% isotropically shaped fibers.Therefore, the minor component is present in at least 5% by weight massof the total fiber composition. Each of the two different shaped fiberscan comprise from about 5% by weight to about 95% by weight. Thespecific percent of each fiber desired depends upon the use of thenonwoven web and specific shape of the fiber.

(4) Material Properties

The fibrous fabrics of the present invention will have a basis weightand opacity that can be measured. Opacity can be measured using TAPPITest Method T 425 om-01 “Opacity of Paper (15/d geometry, Illuminant A/2degrees, 89% Reflectance Backing and Paper Backing)”. The opacity ismeasured as a percentage. The opacity of the fibrous fabric comprisingat least one layer comprising a mixture of shaped fibers havingcross-sectional shapes that are distinct from one another will beseveral percentage points of opacity greater than the fibrous fabriccontaining substantially all round fibers with the same average fiberdenier and basis weight and made of the same polymeric material. Theopacity may be from about 2 to about 50 percentage points greater andcommonly from about 4 to about 30 percentage points greater. Preferably,the opacity will be at least about 5% greater, more preferably 7%greater, and most preferably about 10% greater.

FIG. 16 is a graph of the percent opacity versus basis weight forseveral different fiber shapes and mixtures of shaped fibers. As can beseen, a mixture of 75% trilobal fibers and 25% solid round fibers and amixture of 50% trilobal fibers and 50% solid round fibers both havehigher opacity measurements at equivalent basis weights than 100% hollowround fibers and 100% solid round fibers.

Basis weight is the mass per unit area of the substrate. Independentmeasurements of the mass and area of a specimen substrate are taken andcalculation of the ratio of mass per unit area is made. Preferably, thebasis weight of the layer comprising a mixture of shaped fibers havingcross-sectional shapes that are distinct from one another will be fromabout 1 grams per square meter (gsm) to about 150 gsm depending upon theuse of the fibrous fabric. More preferable basis weights are from about2 gsm to about 30 gsm and from about 4 gsm to about 20 gsm. The basisweight of the total fibrous fabric (including the layer comprising amixture of shaped fibers) is from about 4 gsm to about 500 gsm,preferably from about 4 gsm to about 250 gsm, and more preferably fromabout 5 gsm to about 100 gsm.

Additionally, the fibrous fabrics produced from the shaped fibers willalso exhibit certain mechanical properties, particularly, strength,flexibility, elasticity, extensibility, softness, thickness, andabsorbency. Measures of strength include dry and/or wet tensilestrength. Flexibility is related to stiffness and can attribute tosoftness. Softness is generally described as a physiologically perceivedattribute that is related to both flexibility and texture. Absorbencyrelates to the products' ability to take up fluids as well as thecapacity to retain them. The fibrous fabrics of the present inventionwill also have desirable barrier properties.

Preferably, the fibrous fabric comprising at least one layer comprisinga mixture of shaped fibers having cross-sectional shapes that aredistinct from one another will have a machine direction to cross-machinedirection ratio (MD-to-CD ratio) lower than a fibrous fabric producedwith substantially all trilobal cross-sectional fibers having the samepolymeric material, equivalent fiber denier, and basis weight.Additionally, it is desired that the fibrous fabric of the presentinvention will also have a CD strength and/or total (MD+CD) strengththat is greater than the fibrous fabric with substantially all trilobalcross-sectional fibers. Having the MD-to-CD ratio lower than asubstantially all trilobal layer can be desired as the CD strength ofthe trilobal layers is not as high as desired and the MD strength may betoo high. It is desired to have a relatively high CD strength in a layerso that the basis weight does not need to be increased to achieve therelatively high CD strength. The relatively high CD strength is desiredin some application for keeping the tabs and/or fasteners attached in anabsorbent article. If the MD strength is too high (or the basis weightmust be increased to increase the CD strength creating a very high MDstrength), issues in the converting process may occur. Therefore, to getthe best performance, it is desired to control the MD-to-CD strengthratio and keep a high total strength. The MD and CD tensile strengthscan be measured by ASTM D1682.

FIG. 17 is a chart of the MD-to-CD ratio for several different fibershapes and mixtures of shaped fibers. As can be seen, a mixture of 75%trilobal fibers and 25% solid round fibers and a mixture of 50% trilobalfibers and 50% solid round fibers both have a lower MD-to-CD ratio than100% trilobal fibers. FIG. 18 is a graph of CD tensile strength versusbonding temperature for several different fiber shapes and mixtures ofshaped fibers. As can be seen, a mixture of 75% trilobal fibers and 25%solid round fibers and a mixture of 50% trilobal fibers and 50% solidround fibers both have a higher CD strength at all bonding temperaturesthan 100% trilobal fibers.

(5) Equipment and Processes

The fibrous fabric formed by the equipment of the present invention is aspunmelt nonwoven fibrous fabric. Spunmelt is defined to meanthermoplastic extrusion. Spunmelt includes spunlaid and meltblownprocesses. Spunmelt also includes spunbond fabrics.

The first step in producing a fiber is the heating of raw, extrudablepolymer materials that are typically mixed together as they are meltedand/or transported so as to form a homogeneous melt with properselection of the composition. The melt is conveyed (e.g., via one ormore extruders and/or melt pumps) through capillaries or channels toform fibers. The fibers are then attenuated and collected. The fibersare preferably substantially continuous (i.e., having a length todiameter ratio greater than about 2500:1), and will be referred to asspunlaid fibers. A collection of fibers is combined together using atleast one of heat, pressure, chemical binder, mechanical entanglement,hydraulic entanglement, and combinations thereof resulting in theformation of a nonwoven fibrous fabric. The fibrous fabric may then beincorporated into an article.

Exemplary equipment that can be used to produce any of the shaped fibersand fibrous fabrics as described herein preferably includes thefollowing main parts: (1) Extruders and/or melt pumps to melt, mix andmeter the polymer component, (2) a spin pack system or assemblycomprising a polymer melt distribution system and spinneret thatdelivers a polymer melt(s) to capillaries that have shaped orifices, (3)attenuation device driven by pneumatic air, positive pressure, directforce and/or vacuum by which air drag forces act on a polymer stream toattenuate the fiber diameter to smaller than the orifice overallgeometric shape, (4) fiber laydown region where fibers are collectedunderneath the attenuation device in a random orientation (defined byhaving machine direction and converse direction fiber orientation ratioless than 10), and (5) fiber bonding system that prevents long rangecollective fiber movement. Numerous companies manufacture fiber andfabric making technologies that can be used for the present invention,non-limiting examples include Hills Inc., Reifenhauser GmbH, RieterCorporation, Neumag GmbH, Nordson Fiber Systems and others.

In particular, the equipment described herein is important forincorporating shaped fibers in fabrics for better opacity and mechanicalproperties, where shaped fibers are typically produced using a specialspin pack system that shapes the polymer melt stream as it exits thespinneret.

In accordance with the invention, filaments of mixed shapes, such asround and trilobal, are formed with a spinneret that includes suitablemixtures of orifice geometries so as to form a blend of two or moretypes of fibers or filaments having different shapes or cross-sectionalgeometries at any selected ratios. While fibers having any suitablecross-sectional geometries can be formed, preferred blends of fibers aresolid and/or hollow round fibers with multi-lobal fibers. Exemplarymulti-lobal fibers that can be formed with the spinneret include,without limitation, trilobal, delta, cross shaped, and/or penta-lobal(e.g., shapes such as those described above and depicted in FIGS.3A-3D). Trilobal is a preferred cross section because of the highsurface area to weight ratio of the fiber, and the relative ease ofmanufacturing the spinneret orifice. The system can be configured toform mixed filaments that have the same polymer, the same polymer withdifferent additives, two or more different polymers and/ormulti-component fibers. If multi-component fibers are used,bi-components are the preferred type. However, other multi-componentfiber types can also be formed including, without limitation,sheath/core, islands-in-the-sea, segmented pie, etc. The locations andorientations of the different shaped orifices along the spinneret canalso enhance the formed product as described below.

FIGS. 5-9 depict exemplary embodiments of spinnerets in accordance withthe invention that yield two types of filament shapes or geometries,namely trilobal and round, in ratios from 90:10 to 50:50. However, it isnoted that the invention is not limited to such range of ratios. Inparticular, spinneret configurations are possible that yield fabricshaving different filaments ranging in ratios, for example, from 95:5 to5:95 for two filament shapes (e.g., 80:20 of multi-lobal to round). Inaddition, spinnerets may also include any suitable ratios of more thantwo different shapes of fibers. For example, a spinneret can be formedincluding suitable orifices that forms any selected ratio (such as a25:40:35 ratio) of trilobal to solid round to hollow round filaments.

The spinneret holes or orifices are also preferably oriented for certainorifice geometries in a selected manner based upon the direction atwhich a quenching medium, such as quench air, is directed to contact thefibers emerging from the spinneret. For example, when forming trilobalfilaments from trilobal shaped spinneret orifices (e.g., such as fibersdepicted in FIGS. 3A and 3D), optimum spinning conditions can beachieved when a single tip portion, leg or lobe (e.g., a lobe 1 asindicated in FIGS. 3A and 3D) of at least some of the trilobal fibers isaligned or oriented in a direction toward or facing a source ofquenching medium. Other multi-lobal fiber configurations can also bealigned in a similar manner as the arrangement of trilobal fibersdescribed above to achieve enhanced spinning conditions. The spinneretorificies are therefore configured to achieve such an alignment for themulti-lobal fibers emerging from the spinneret. The orientation of themulti-lobal orifices on a spinneret in this manner is very important forcommercially producing fabrics as described herein, particularly whenutilizing spinnerets having more than one multi-lobal orifice per 1 cm².

In the present invention, fiber mixtures are produced by distributingthe various orifice geometries along the bottom or outlet surface of thespinneret to produce a relatively uniform fiber distribution of shapeson fiber laydown through their spatial location across the spinneretface. The spinneret includes generally vertical channels or counterboresthat extend from a top or inlet surface of the spinneret to spinneretorifices disposed at the bottom or outlet surface of the spinneret.Several examples of spinnerets are shown in FIGS. 5-9 with differentspinneret orifice distributions. However, it is noted that any suitablespinneret orifice distribution can be configured for the spinneret inaccordance with the invention (i.e., the invention is in no way limitedto these examples).

Referring to FIG. 5A, a spinneret 2 is depicted including a distributionof orifices that yields a ratio of 90:10 of trilobal to solid roundfilaments. FIGS. 5B and 5C respectively depict round orifice 4 andtrilobal orifice 6 geometries as can be seen along the bottom (i.e.,outlet) surface of the spinneret. An enlarged view of a portion ofspinneret 2 is depicted in FIG. 5D, where it can be seen that thetrilobal orifices 6 are all arranged along the outlet surface of thespinneret in the same or substantially similar alignment with eachother. In particular, the trilobal orifices 6 are formed in thespinneret 2 such that a single lobe of each of the trilobal fibersemerging from the spinneret is aligned in a direction that generallyfaces a source of quench air. In other words, the trilobal fibers areformed such that a single lobe of each of these fibers is oriented in adirection that opposes a direction in which quench air (shown by arrows8 in FIG. 5A) is flowing from the quench source to contact the fibers.

This trilobal orientation allows the quench air to contact the majorityof all the lobes of the trilobal fibers that are aligned with respect tothe quench air, resulting in highly uniform quenching and physicalproperties for the fibers. This orientation also prevents the quench airfrom potentially rotating the trilobal fibers, which would have anadverse effect and cause turbulence and filament-to-filament collisionsin the spinning process. As noted above, a spinneret including anynumber and types of multi-lobal orifices that produce multi-lobal fiberswill benefit from a configuration similar to that depicted in FIGS.5A-5D (as well as FIGS. 6-9 as described below), where the fibers areformed such that a lobe of at least some of the fibers emerging from thespinneret is aligned in a direction that faces the quench source andgenerally opposes the flow direction of a quench air used to quench thefibers.

FIGS. 6A-6B and 7A-7B depict a spinneret including solid round orifices4 and trilobal orifices 6, where spinneret 10 of FIG. 6A includes a75:25 ratio of trilobal to round orifices and spinneret 12 of FIG. 7Aincludes a 50:50 ratio of trilobal to round orifices. The trilobalorifices in each spinneret 10, 12 are aligned in a similar manner as thetrilobal orifices for spinneret 2 described above and depicted in FIG.5A, such that a single lobe of each trilobal fiber 6 emerging from thespinneret is aligned in a direction facing a quench air supply sourceand generally opposing the flow direction of quench air (shown by arrows8) that is used to quench the fibers.

FIG. 8A depicts a spinneret 14 that includes a 50:50 ratio of trilobalorifices 6 and hollow round orifices 7 (i.e., orifices that yield hollowround fibers). The trilobal orifices are arranged in spinneret 14 suchthat the trilobal fibers formed are aligned with respect to the quenchair (shown by arrows 8) in the same manner as described above for theembodiments depicted in FIGS. 5-7.

Referring to FIG. 9A, a spinneret 20 is depicted that includes a 75:25ratio of trilobal orifices 6 to solid round orifices 4. However, in thisembodiment, as can be seen from FIG. 9B, fibers emerging from spinneret20 are subjected to a two-sided quench, where two streams of quench airare directed in generally opposing directions with respect to each othertoward the fibers and oriented at opposing sides of the spinneret(depicted as arrows 8 and 9 in FIG. 9B). Two-sided quenching is oftendesired in spunbond processing to achieve rapid and effective cooling ofthe extruded fibers. To achieve a similar benefit as described above forthe trilobal fibers being contacted with the quench air, the orientationor alignment of trilobal orifices 6 disposed along one section ofspinneret 20 differs with respect to the orientation of trilobalorifices 6 disposed along at least one other section of the spinneret.

In particular, as can be seen in FIG. 9B, spinneret 20 includes twohalves that are separated along a centerline (indicated by dashed line22 in FIG. 9B) extending the length (i.e., between longitudinal ends) ofthe spinneret. The trilobal orifices 6 on a first half section 24 of thespinneret are aligned or oriented such that a single lobe of each of thetrilobal fibers emerging from spinneret 20 is aligned in a directionthat faces a quench supply providing the closest source of quench air(indicated by arrows 9) that quenches these fibers. The trilobalorifices 6 on a second half section 26 of the spinneret, as can be seenfrom the outlet surface of spinneret 20, have a reverse orientation(i.e., a 180° rotational orientation) in relation to the trilobalorifices 6 on the first half section 24, such that a lobe of each of thetrilobal fibers emerging from spinneret 20 is aligned in a directionthat faces a quench supply providing the closest source of quench air(indicated by arrows 8) that quenches these fibers.

Depending upon the directions of quenching medium flowing toward fibersemerging from the spinneret, spinnerets can be designed in accordancewith the invention including the same type of multi-lobal orificesformed within the spinneret but with groups or sections of multi-lobalorifices being arranged along the spinneret in any number of differentorientations with respect to multi-lobal orifices of other sectionsarranged along the spinneret, which facilitates the formation ofmulti-lobal fibers oriented in a similar manner as described above withrespect to the varying directions of quenching medium flow aimed towardthe fibers. For example, a spinneret can include two or more sections ofthe same multi-lobal orifices, where the multi-lobal orifices of onesection are oriented on the outlet surface of the spinneret at anysuitable angle of rotation (e.g., 45°, 90°, 135°, 180°, etc.) withrespect to multi-lobal orifices of one or more other sections of thespinneret so as to facilitate alignment of a single lobe of at leastsome multi-lobal fibers of a section in a direction generally facing aclosest source of quenching medium that is aimed toward this section offibers.

Any suitable selection of grouping of orifices with different shapes orgeometries can be provided on the spinneret to achieve a desiredgrouping of resultant mixed filaments or fibers that are extruded fromthe spinneret. While the embodiments described above and depicted inFIGS. 5-9 show orifices arranged in generally straight or linear rowsand columns, the orientation of spinneret orifices is not limited tosuch arrangements. Any suitable alignment of spinneret orifices (e.g.,selectively patterned or randomized) may be chosen to reduce turbulenceand optimize fiber spinning and maximize quench rate. For example, insome applications it may be desirable to have random orientation to aidin the reduction of roping or other non-uniformity issues.

In another embodiment of the invention, the spinneret with mixed orificegeometries (e.g., any of the spinnerets described above and depicted inFIGS. 5-9) can be a full fabric width spinneret (i.e., a spinnerethaving a longitudinal dimension of at least about 500 millimeters).

In the spinneret embodiment of FIGS. 9A and 9B, the spinneret orificesare arranged such that substantially entirely round orifices 4 aredisposed at a selected distance from each of the lengthwise orlongitudinal ends of spinneret 20 (as shown by bracket 28 of FIG. 9B).This selected distance from the longitudinal ends of the spinneretcorresponds with the edge of the fiber product that is formed and whichis typically trimmed or removed in some manner from the product. It isgenerally easier to yield good spinning and prevent or minimize filamentbreaks with round spinneret orifices, and round orifices are also lesscostly to manufacture than multi-lobal orifices. Thus, as can be seen inFIG. 9B, substantially no trilobal orifices are provided within thisselected outer area of the spinneret outlet surface (the area indicatedby bracket 28).

Preferably, round orifices 4 are also disposed along all of the outeredges of the spinneret and also at or near the middle portion of thespinneret (as depicted in FIG. 9B), since this is typically whereturbulence in fiber flow is the greatest, and round fibers are lesssusceptible to twisting or breaking when exposed to turbulence incomparison to multi-lobal fibers. Thus, a spinneret configuration suchas is depicted in FIGS. 9A and 9B provides enhanced fabric or otherfiber product formation by minimizing twisting or breakage of fibers(particularly of the multi-lobal fibers) as well as enhancing thequenching of the formed fibers.

In addition to enhancing fiber product formation with mixed filamentgeometries by designing the spinneret in the manner described above,other components of the spin pack assembly can be designed to improvesystem performance and enhance the fiber product. A flexible spin packsystem or assembly is provided in accordance with the invention, wherethe spin pack system is utilized in an economical and efficient mannerto produce various types of mixed filaments. The spin pack system caninclude any suitable spinneret, such as the spinnerets described above.It is preferable that the flexible spin pack system, or at leastportions of the system (e.g., metering/distribution plates) areconfigured to be retrofitted to existing spunlaid lines. The term“spunlaid” is used herein to describe a spinning system that includesthe extruder, polymer metering system, spinpack, cooling section, fiberattenuation, fiber laydown and deposition onto a belt or drum andvacuum. The spunlaid system does not denote the type of fiberconsolidation.

A spunbond line includes a spunlaid line and thermal point bonding. Theequipment before the fiber consolidation is substantially similar oridentical on a spunbond line and a spunlaid line. An exemplaryembodiment of a spunbond line is described below and depicted in FIG.15.

The flexible spin pack system of the present invention includes ametering/distribution system that effectively meters and distributesmolten polymer to the various spinneret orifices. Preferably, the spinpack system utilizes one or more low cost metering/distribution plates.The metering/distribution plates can be of any suitable types, such asthose described in U.S. Pat. No. 5,162,074 (“the '074 patent”), which isincorporated herein by reference in its entirety, so as to deliver andmeter the polymer in a homo or multipolymer system to each spinneretorifice. In particular, a metering/distribution plate includeshorizontal passages (referred to as channels) and/or vertical flowpassages (referred to as through-holes) that extend within the plate soas to facilitate metering and/or distribution of polymer flow throughthe plate and between a top or inlet surface of the plate and a bottomor outlet surface of the plate, which in turn facilitates the flow ofpolymer to the spinneret.

An exemplary embodiment of an etched metering/distribution plate 30 isdepicted in FIGS. 10A and 10B. The plate includes a number of passagesor channels etched within and extending generally horizontally along anupper or inlet surface of plate 30. Alternatively, it is noted that thechannels may be formed via a suitable machining process. The generallyhorizontally-extending channels are formed having selected dimensions(e.g., lengths, widths and depths) that facilitate at least partialcontrol of polymer flow through the metering/distribution plate to thespinneret. The generally horizontally-extending channels further extendto and are in fluid communication with vertical passages orthrough-holes that extend generally vertically within plate 30 to abottom or outlet surface of the plate. The through-holes are aligned onthe metering/distribution plate such that, when the plate is placed inthe spin pack assembly over and in contact with the spinneret, thethrough-holes are in fluid communication with capillaries orcounterbores of the spinneret that lead to the spinneret orifices.

Alternatively, it is noted that the vertical orientation of the etchedor machined metering/distribution plate with respect to the spinneretcan also be reversed, such that the top or inlet surface of themetering/distribution plate includes the through-holes and the bottom oroutlet surface of the plate includes the generally horizontal channelsthat are in communication with the counterbores of the spinneret.

The channel dimensions of each channel of the metering/distributionplate can remain generally constant or, alternatively, one or morechannel dimensions can vary along the length of the channel between theupstream channel end (i.e., the channel end that serves as the channelinlet that receives molten polymer from an upstream component of thespin pack assembly) and the downstream channel end (i.e., the channelend that is adjacent and communicates with the vertical through-hole ofthe plate).

In addition, the transverse cross-sectional geometries of each of themetering/distribution plate channels can have any suitable shapes, withone or more channel walls being generally planar, curved (e.g., rounded,concave or convex) and/or pitched at any selected slopes between theupstream and downstream channel ends. In an exemplary embodiment, theetched (or machined) channels in the metering/distribution plate caninclude a transverse cross-sectional shape including a generally concavebottom surface and generally flat or planar side wall surfaces. Othercross-sectional channel shapes can also be provided for themetering/distribution plate. In addition, the metering/distributionplate channels can be formed with a variety of different length to widthand width to depth ratios, where the selection of specific dimensionalratios will depend upon a particular application. Exemplary channelwidth to channel depth ratios for the metering/distribution platechannels are in the range of about 1.5:1 to about 15:1, but these ratioscan also be larger or smaller depending upon a particular application.

The vertically extending through-holes of the metering/distributionplate can also have any suitable dimensions to facilitate a desired flowof polymer through the plate. However, it is noted that there is greaterflexibility in selection of dimensions for the etched (or machined) andgenerally horizontally extending channels of the metering/distributionplate, and polymer flow control through the plate can be controlled to alarge degree by adjustment of these channel dimensions for a particularapplication. Thus, a suitable etching process provides an economical andeffective metering/distribution plate that includes elaborate channelswith varying dimensions.

The metering/distribution plate serves a distribution function bydelivering molten polymer, via the various channels in the plate, toselected throughbores and orifices of the spinneret. The plate furtherserves a metering function in that each passage (e.g., etched ormachined channel and/or through-hole) that corresponds with a respectivespinneret orifice can be selectively dimensioned (e.g., by selectingetched or machined channel dimensions such as lengths, widths, depths,diameters, etc.) so as to control the pressure drop of the polymerflowing through the passage and thus the delivery of polymer at adesired flow rate to the respective spinneret orifice. This in turnfacilitates the control of the formation of a fiber through therespective spinneret orifice at a selected denier and cross-sectionaldimension (e.g., diameter). The term “denier,” as used herein, refers tothe linear mass density of a fiber and is defined as the mass in gramsper 9,000 meters of the fiber.

As noted above, metering/distribution plates can be made by a low costetching process, such as the process described in the '074 patent, toinclude horizontally aligned channels and vertically alignedthrough-holes that form the passages in the plates. Such channels andthrough-holes can also be formed in the plate by a machining process.Alternatively, the passages of the plates can be machined drilled andvertically aligned through-holes, with the drilled through-holes havingsuitable dimensions to control pressure drop in a similar manner as thehorizontal channels of an etched or machined plate. The use of drilledmetering plates is described in further detail below.

The use of a metering/distribution plate in a spin pack system inaccordance with the present invention provides a number of advantages.In particular, the metering/distribution plate decouples the metering ofmolten polymer from the spinneret orifice geometry, which allows fibersto be produced from each spinning orifice at one or more desired deniersand also allows for optimization of the spinneret orifice geometry forvarious other functions, such as polymer shear rate, jet stretch (asdescribed below), as well as final fiber cross section geometry (e.g.,forming sharper or more well-defined multi-lobal fibers). One skilled inthe art will recognize that the final geometry of an extruded fiber isdetermined, at least in part, by the design (e.g., geometry anddimensions) of the spinneret orifice. For example, if a sharp trilobalfiber is desired with long, extended or skinny legs or lobes, thespinneret orifice will also require such a shape. However, such a shapemay not be consistent with the metering requirements to produce thedesired denier unless at least a portion of the metering can becontrolled with a metering plate or some other suitable pressure controlmechanism disposed upstream of the spinneret orifice.

Another advantage of the metering/distribution plate in accordance withthe invention is that the plate can be changed (i.e., substituted withanother plate) in the spin pack to facilitate a change of polymer flowto selected spinneret orifices. This results in a relatively easy andcost effective mechanism for changing the deniers of mixed fibers formedwith different shapes in a single system without necessarily requiring amodification to the spinneret.

A still further advantage of the metering/distribution plate inaccordance with the invention is that the plate provides for a low costretrofit into existing and commercially plentiful machines, such asmachines manufactured by Reifenhauser GmbH (Germany) and described inU.S. Pat. No. 5,814,349 (“the '349 patent”), which is incorporatedherein by reference in its entirety. The '349 patent describes a“closed” system, where quench air is used to both quench and draw thefibers. The metering/distribution plate of the invention is equallyadvantageous in “open” systems, where a separate source of compressedair is used to draw the fibers, such as the system described in U.S.Pat. No. 6,183,684, which is incorporated herein in by reference in itsentirety.

A change in metering of molten polymer to the spinneret orifices may benecessary based upon any number of desired changes in the physicaldimensions or properties of the fibers formed and/or the processconditions during system operation. For example, any of the followingchanges in a system may require a change in metering of polymer flowthrough the spinneret orifices: a change in total polymer throughput(e.g., an increase in polymer throughput or mass flow rate may requiresa reduction in pressure drop to maintain desired fiber denier), a changein denier for one or more sets of fibers having differentcross-sectional geometries, a change in temperature of polymer flowingthrough the spin pack assembly (which changes viscosity), and a changein the ratio of different shaped spinneret orifices (which results in adifferent number of formed fibers having different cross-sectionalgeometries with respect to the total number of fibers formed from thespinneret) and/or arrangement or pattern of spinneret orifices disposedon the spinneret outlet surface (e.g., different arrangements of roundorifices to multi-lobal orifices across the spinneret outlet surface).

In designing a spin pack assembly, one or more metering/distributionplates may be provided in the spin pack assembly. For example, a singlemetering/distribution plate may be provided. Alternatively, two moremore metering/distribution plates can be provided in a verticallystacked alignment with each other within the spin pack assembly, wherethe flow passages of two adjacent plates are in fluid communication witheach other to facilitate the flow of molten polymer material between thetwo plates.

As noted above, the metering/distribution plate can be designed for aparticular spin pack system and mixed filament spinneret so as todecouple the pressure drop from the shear rate and jet stretch, all ofwhich are parameters that otherwise are typically addressed whenselecting geometric designs for the spinneret orifices. In order tomaintain good fiber spinning for a particular application, it isnecessary to control pressure drop, shear rate and jet stretch withinpredefined values. The pressure drop of polymer through a spinneretorifice will depend upon the orifice geometry. For example, in a roundspinneret orifice, the pressure drop through the orifice can becalculated as follows (see, e.g., Dynisco, “Extrusion ProcessorsHandbook”, 2^(nd) Edition): $\begin{matrix}{P = \frac{2\quad L\quad{Tw}}{R}} & (1)\end{matrix}$where

-   -   P=pressure drop (psi)    -   L=Length of capillary (inches)    -   Tw=Shear stress at wall (psi)    -   R=radius of capillary (inches)        The shear rate is defined as: $\begin{matrix}        {\gamma = \frac{3.3Q}{R^{3}}} & (2)        \end{matrix}$        Where    -   γ=shear rate (sec⁻¹)    -   Q=flow rate (in³/sec)    -   R=radius of capillary (inches)

The jet stretch is defined as the ratio of the maximum spinning velocityof the fibers to the velocity of the polymer at the exit of thespinneret hole.

Since at least two types of different shaped fibers are spun in mixedfilament spinning, it is necessary to independently control the pressuredrop, shear rate and jet stretch through each orifice type (i.e.,different shape and/or diameter). By providing greater control in thepressure drop upstream from the spinneret orifice (e.g., via a suitablemetering/distribution plate), more flexibility is provided in designingspinneret orifice geometries that are desirable for a particularapplication. This is achieved in a number of different embodiments inaccordance with the invention.

One embodiment employs a spin pack assembly and two metering pumps asdepicted in FIG. 11. In particular, a spin pack assembly 40 includes, ina vertically stacked alignment, a pack top 42, a filter support plate 44disposed beneath the pack top, filters disposed within a cavity 43formed between corresponding grooved portions of the pack top and filtersupport plate to filter the polymer flowing through the assembly, ametering/distribution plate 46 disposed beneath the filter support plateand including suitable channels for directing polymer through plate 46and to the spinneret, and a spinneret 48 disposed beneath plate 46 toreceived metered polymer to the various orifices of the spinneret.

The filter support plate 44 includes any suitable series of channels orcavities disposed at the bottom or outlet surface of the filter supportplate to facilitate fluid communication between polymer flow passages ofthe filter support plate and the passages of the metering/distributionplate. For example, the outlet surface of the filter support plate mayinclude machined channels that correspond with the etched or machinedchannels of the metering/distribution plate (or vertical through-holesof a drilled metering/distribution plate). Alternatively (or in additionto the channels) the outlet surface of the filter support may includeone or more cavities to facilitate the formation of one or more meltpools of polymer material within the filter support plate that are to bedirected to the metering/distribution plate. When providing cavitieswithin the filter support plate to form melt pools, a valve plate isthen provided between the filter support plate and themetering/distribution plate and includes flow passages extending throughthe valve plate that are in fluid communication with the melt pool(s)and the passages of the metering/distribution plate.

Depending upon a particular application, a series ofmetering/distribution plates could also be provided in the spin packassembly of FIG. 11 (as well as the spin pack assembly of FIG. 12),where the metering/distribution plates are arranged in a verticallystacked alignment with respect to each other and include appropriatelyaligned passages (i.e., channels and/or through-holes) to facilitatefluid communication between two adjacent plates.

The spinneret includes orifices having different geometries, where theorifices can include any two or more cross-sectional geometries and atany selected ratio of geometries (e.g., spinneret 48 can be any of thetypes described above and depicted in FIGS. 5-9). A pump block 50,disposed above pack top 42, supports two metering pumps 52 and 54. Themetering pumps deliver molten polymer through the pump block and to thespin pack assembly, where the molten polymer is then filtered anddirected to the metering/distribution plate(s) for distribution andmetering to the different shaped spinneret orifices.

It is noted that, in certain embodiments, the pack top is not needed andthus does not form part of the spin pack. Thus, the pack top in theassembly of FIG. 11 (as well as the embodiments of FIGS. 12 and 13) canbe removed such that the filter support plate lies directly below thepump block.

The flow channels through the various components of the two meteringpump system of FIG. 11 can be designed such that one pump feeds one onetype of spinneret orifice (e.g. multi-lobal) and the other pump feedsanother type of spinneret orifice (e.g., round). In this two meteringpump embodiment, the pump speeds can be selected to largely controlmetering of polymer material flowing through the metering/distributionplate and spinneret, such that the metering/distribution plate servesprimarily to distribute the polymer to the different spinneret orifices.If more than two polymer components (or two streams of the same polymercomponent including different additives) are desired to form the mixedfilaments, each additional component would require an extra meteringpump. The polymer temperatures fed to or from the two pumps may also beadjusted to assist in acheiving desirable polymer conditions including,without limitation, enhanced cross sections, suitable shear rates, etc.The metering/distribution plate can also be used to distribute polymerfrom the filtration areas to the two types of spinneret orifices. If themetering/distribution plate is manufactured by low cost techniques suchas etching, two or more plates may be selectively exchanged within thespin pack assembly 40 to modify polymer flows to different spinneretorifices (resulting, e.g., in different fibers deniers) at a low costand with relative ease.

In another embodiment depicted in FIG. 12, a spin pack assembly 60includes, in a vertically stacked alignment, a pack top 62, a filtersupport plate 66 disposed below the pack top, a filter formed betweencorresponding grooved portions of the pack top and filter support plateto filter the polymer flowing through the assembly, ametering/distribution plate 68 disposed below the filter support plate,and a spinneret 70 disposed below plate 68. The spinneret includes mixedorifice geometries and can be of any suitable type (such as the typesdescribed above and depicted in FIGS. 5-9). A pump block 72 is disposedabove the pack top and supports a single metering pump 74 to delivermolten polymer to assembly 60. Fluid communication between the filtersupport plate and the metering/distribution plate can be provided in anysuitable manner (e.g., similar to that described above for theembodiment of FIG. 11).

During operation, polymer material is delivered by metering pump 74 intoassembly 60, where the polymer material is filtered and then directedthrough the various passages of the metering/distribution plate. Themetering/distribution plate 68 is designed in a suitable manner asdescribed above to receive molten polymer from the filter support plate66, and to at least partially control the pressure drop of polymerflowing to each spinneret orifice type. The control of the pressure dropthrough the metering/distribution plate facilitates effective control ofthe denier of each of the mixed filament fibers extruded from thespinneret.

A further embodiment is depicted in FIG. 13 and includes a spin packassembly 80 including, in a vertically stacked alignment, a pack top 82that includes a filter 84 to filter molten polymer flowing through theassembly, a filter support plate 86 disposed below the pack top, and aspinneret 88 disposed below the filter support plate. As in the previousembodiment depicted in FIG. 12, a single metering pump 92, which issupported by pump block 90 disposed above pack top 82, delivers moltenpolymer to assembly 80. However, assembly 80 does not include ametering/distribution plate. Rather, a cavity 87 is formed within filtersupport plate 86 at a location where the filter support plate engagesthe spinneret. The cavity 87 facilitates the formation of a pressurizedmelt pool of molten polymer as polymer is delivered through the filterto counterbores in the spinneret that lead to the various spinneretorifices. Alternatively, it is noted that the cavity in which the meltpool forms could be provided in the spinneret or both the filter supportplate and the spinneret. In this embodiment, the vertically-extendingcapillaries or counterbores of the spinneret are designed with suitabledimensions (e.g., suitable length to diameter ratios) to facilitate thebalance of pressure drops of polymer flow through the spinneret prior toemerging from the spinneret orifices in a manner similar to that inwhich the metering/distribution plate is designed as in the previousembodiments described above and depicted in FIGS. 11 and 12.

The embodiment of FIG. 13 is primarily suitable when the polymerpressure within the melt pool remains at a specific value. Thus, whileit is possible to provide a spin pack assembly without the use of ametering/distribution plate to form the mixed filament products asdescribed herein (where the pressure drop, shear rate and jet stretch iscontrolled by designing suitable channels and orifices in thespinneret), the use of a metering/distribution plate to control pressuredrop, which in turn enables control of the deniers of the mixed filamentfibers, is applicable to a much wider range of applications and is thuspreferable over spin pack assemblies that do not employ suchmetering/distribution plates.

As noted above, etched (or machined) metering/distribution plates (suchas the plate depicted in FIGS. 10A and 10B) are effective in at leastpartially controlling pressure drop to achieve the desired fiber sizeand denier of different shaped fibers. However, metering/distributionplates can also be manufactured utilizing a drilling process, wherepassages of varying cross-sectional dimensions are formed by drillingthrough the plate. In a drilled metering/distribution plate, there areno horizontally extending channels such as in the etched (or machined)plate. Rather, the passages of the drilled plate are generally verticalthrough-holes extending between the top or inlet surface of the plateand the bottom or outlet surface of the plate. A drilled metering platetypically requires a significant thickness to facilitate a sufficienthole length to achieve the desired control of pressure drop through theplate. In addition, different diameter holes can be used to control andadjust the flow rate through the drilled metering plate/spinneretcombination to adjust the deniers of the two types of fibers being spunfrom the same melt pool.

An exemplary embodiment of a drilled metering/distribution plate 96 isdepicted in FIGS. 14A and 14B. In this embodiment, plate 96 has asuitable thickness to facilitate the formation of through-holes ofsuitable lengths. The lengths and cross-sectional dimensions of thethrough-holes (e.g., the length to diameter ratios of the through-holes)can be selected in a similar manner as the channel dimensions in anetched (or machined) metering/distribution plate to facilitate controlof pressure drop of polymer flow through the different shaped spinneretorifices, which in turn controls the deniers of different shaped fibers.

For example, through-holes can be drilled in the plate of varyingdiameters (such as through-holes 97 and 98 of plate 96 depicted in FIGS.14A and 14B) to selectively adjust the flow rate through the drilledmetering plate/spinneret combination, which in turn controls the deniersof the two types of filaments being spun from the same metering pumpand/or melt pool. By using different metering plates, different denierratios between the two types of spinneret orifices can be obtainedwithout requiring a new spinneret.

However, it is noted that drilled metering/distribution plates aresignificantly more expensive to produce (e.g., as much as a tenfold orgreater increase in cost) than etched metering/distribution plates, dueat least in part to the labor-intensive requirements of drillingthousands of holes per meter along the surface of the plate. Inaddition, since the drilled plate through-holes are vertically aligned,rather than having a horizontal channel component as in the etchedplates, controlling pressure drop in different applications may requiresignificant changes in the drilled plate thicknesses. Thus, certaindrilled plates can be very thick (and heavy), depending upon certainapplications that require certain through-hole dimensions. This rendersthe drilled plates less suitable for exchanging or retrofitting withinexisting spin pack assemblies. In contrast, etched metering/distributionplates with different channel dimensions can be easily changed in anexisting spin pack assembly while maintaining generally the samethickness of the plate dimensions (since the horizontal etched channelcomponent is changed). In addition, due to their economic design, etchedchannel plates can be disposable. Thus, the use of lower cost, etchedmetering/distribution plates is preferred in the various spin packassembly embodiments of the invention.

The combination of one or more metering/distribution plates andspinnerets with selective orientations of orifice geometries in a spinpack system or assembly is highly effective in producing a homogenousmixture of shaped fibers in the nonwoven fabrics and other productsdescribed herein. As noted above, when utilizing a single spinneret withdifferent shaped orifices, it is extremely important to be able to atleast partially control the pressure drop upstream of the spinneretorifices to form fibers with mixed geometries. The mass flow ratethrough each spinneret orifice type will be different due to pressuredrop differences as explained above. Further, at the same or similarmass flow rate in each spinneret orifice type, the spinningcharacteristics are different and do not lead to identical fiberdiameter values. Therefore, the combination of the above-describedfeatures for the spinneret and spin pack assembly render enhancedcontrol and production of fiber products including mixed filamentgeometries.

Spinning

The process of melt spinning is the most preferred embodiment forforming mixed filament products described herein. In melt spinning,there is no intentional mass loss in the extrudate. Solution spinningmay be used for producing fibers from cellulose, cellulosic derivatives,starch, and protein.

Spinning will typically occur at 100° C. to about 350° C. The processingtemperature is determined by the chemical nature, molecular weights andconcentration of each component. Fiber spinning speeds of greater than100 meters/minute are required. Preferably, the fiber spinning speed isfrom about 500 to about 14,000 meters/minute. The spinning may involvedirect spinning, using techniques such as spunlaid or meltblown, as longas the fibers are mostly continuous in nature. Continuous fibers arehereby defined as having length to width ratio greater than about2500:1.

The fibers and fabrics made in the present invention often contain afinish applied after formation to improve performance or tactileproperties. These finishes typically are hydrophilic or hydrophobic innature and are used to improve the performance of articles containingthe finish. For example, Goulston Technologies' Lurol 9519 can be usedwith polypropylene and polyester to impart a semi-durable hydrophilicfinish.

FIG. 15 depicts a schematic of a typical spunbond line 100 utilizing asingle polymer source. In this embodiment, any combination of the abovedescribed metering/distribution plates, melt pools and/or spinnerets maybe employed (e.g., the types of systems described above and depicted inFIGS. 5-10, 12 and 13) in the spin pack assembly 118. Briefly, thespunbond system includes a hopper 110 into which pellets of polymer areplaced. The polymer is fed from hopper 110 to a screw extruder 112,where the polymer is melted. The molten polymer flows through heatedpipe 114 into metering pump 116 and spin pack assembly 118, including aspinneret 120 with orifices through which fibers 122 are extruded. Theextruded fibers 122 are quenched with a quenching medium 124 (e.g.,air), and are subsequently directed into a drawing unit 126 (e.g.,aspirator). Upon exiting the drawing unit 126, the attenuated fibers 128are laid down upon a continuous screen belt 130 supported and driven byrolls 132 and 134. The screen belt conveys the prebonded web of fibersfrom the lay down location to calendar rolls 144 and 146. The extruderand melt pumps are chosen based on the polymers desired.

While system 100 utilizes a single melt/metering pump, an alternativesystem can employ two or more metering pumps (e.g., for use with thespin pack assembly of FIG. 11). In addition, system 100 may be used witha single polymer or a blend of polymers.

EQUIPMENT EXAMPLES

A spin pack assembly including an etched metering/distribution plate(MDP) and having a configuration similar to the assembly described aboveand depicted in FIG. 12 was used in conducting each of the four examplesdescribed below, with results tabulated in Tables 1 and 2. The assemblyincluded a mixed filament spinneret including 20,000 orifices ofmulti-lobal and solid round geometric configurations. In particular, themulti-lobal fibers of Examples 1-3 are trilobal fibers (e.g., similar tothe fiber depicted in FIG. 3A), while the multi-lobal fibers of Example4 are cross-shaped fibers having four lobes (e.g., similar to the fiberdepicted in FIG. 3B). A fiber spinning speed was set for each example at4,000 meters per minute (MPM).

In each example, a different MDP was utilized in the spin pack assembly,where the horizontally etched MDP channel dimensions (length, width,depth) that lead to each of the multi-lobal and round spinneret orificeswere modified. The MDP channels were desiged to yield equal residencetimes for the polymer material flowing through the spinneret orifices.Table 1 tabulates the MDP channel and spinneret orifice dimensionalinformation for forming the multi-lobal fibers of each example, as wellas the calculated total pressure drop (i.e., pressure drop through theMDP and the spinneret orifice), shear rate, jet stretch, denier perfiber (dpf) and fiber size for these fibers. Table 2 tabulates the sameinformation for the round fibers that are formed in each example. TABLE1 Multi-lobal Fibers Example 1 Example 2 Example 3 Example 4 Spin Speed4000 4000 4000 4000 (MPM) Polymer PP PP PET PP Fiber Tri- Tri- Tri-Cross Cross-section lobal lobal lobal # of 16000 16000 16000 16000Filaments MDP width: width: width: width: channel 0.7 0.7 0.7 0.7dimensions depth: depth: depth: depth: (mm) 0.381 0.381 0.381 0.381length: length: length: length: 11.69 9 22.6 9.9 Spinneret Leg L: Leg L:Leg L: Leg L: Orifice 0.1705 0.1705 0.1705 0.18 dimensions Leg W: Leg W:Leg W: Leg W: (mm) 0.127 0.127 0.127 0.125 Area: Area: Area: Area: 0.0820.082 0.082 0.099 Total Pressure 750 750 750 750 Drop (psi) Fiber Size0.67 0.89 0.67 0.89 (g/hole/min) Denier (dpf) 1.5 2 1.5 2 Shear rate5733 7644 3822 6125 Jet velocity 10.4 13.9 6.95 8.63 (MPM) Jet stretch384 288 576 463

TABLE 2 Solid Round Fibers Example 1 Example 2 Example 3 Example 4 SpinSpeed 4000 4000 4000 4000 (MPM) Polymer PP PP PET PP # of 4000 4000 40004000 Filaments MDP width: width: width: width: channel 0.7 0.7 0.7 0.7dimensions depth: depth: depth: depth: (mm) 0.381 0.381 0.381 0.381length: length: length: length: 11.3 16.79 22.3 16.8 Spinneret diameter:diameter: diameter: diameter: Orifice 0.35 0.35 0.35 0.35 dimensionslength: length: length: length: (mm) 1.4 1.4 1.4 1.4 Total Pressure 750750 750 751 Drop (psi) Fiber Size 0.67 0.44 0.67 0.44 (g/hole/min)Denier (dpf) 1.5 1 1.5 1 Shear rate 3381 2254 2254 2254 Jet velocity8.88 5.92 3.95 8.63 (MPM) Jet stretch 450 675 1013 463

As can be seen from the tabulated information, the spin pack assembly ofExamples 1-3 utilizes the same spinneret, which has a 75:25 ratio oftrilobal to round fibers. The spinneret used for Example 4 is differentfrom the previous examples in that the orifices are cross-shaped, with a75:25 ratio of cross-shaped fibers to round fibers. In addition, asingle molten polymer material, either polypropylene (PP) orpolyethylene terephthalate (PET), is utilized to form both the round andmulti-lobal fibers of each example. Example 1 serves as a reference,while certain modifications are made to the equipment and/or polymermaterials in each of Examples 2-4 for comparison purposes with Example1.

In a comparison of Example 1 and Example 2, the channel dimensions ofthe MDP are modified in Example 2 for both the trilobal and round fibersso as to modify the dpf of the fibers. This demonstrates the ease withwhich fiber denier values can be modified by replacing one MDP withanother MDP having different channel dimensions.

In comparing Example 1 with Example 3, the polymer material used to formthe fibers is changed from polypropylene to polyethylene terephthalate.However, due to the change in MDP channel dimensions, the denier perfiber for each of the round and trilobal fibers is maintained at thesame value. This example demonstrates that, when a change in polymermaterial and/or rheology occurs, the MDP channel dimensions can beselectively adjusted (e.g., by replacing one etched MDP with anotheretched MDP in the spin pack assembly) to maintain fiber deniers atdesired values.

As noted above, the spinneret of the assembly is changed in Example 4,where the trilobal spinneret orifices are replaced with cross-shapedspinneret orifices. This example illustrates that the MDP channeldimensions can be easily changed (e.g., by switching plates) toeffectively control pressure drop and fiber denier while allowing moreflexibility in spinneret orifice designs and dimensions.

While a drilled MDP could also be utilized in each of these examples, itis preferable to utilize an etched MDP for all of the reasons notedabove (e.g., costs, greater flexibility in channel dimensions for a spinpack assembly having specified dimensions, etc.).

(6) Articles

The spunmelt fibrous fabrics formed in accordance with the presentinvention are nonwoven webs. The fibrous fabric may comprise one or morelayers. If the fibrous fabric contains more than one layer, the layersare typically consolidated by thermal point-bonding or other techniquesto attain strength, integrity and certain aesthetic characteristics. Alayer is part of (or all of) a fibrous fabric that is produced in aseparate fiber lay down or forming step and will have the same fibersintimately mixed throughout the layer. A laminate is defined as a two ormore nonwoven layers contacting along at least a portion of theirrespective planar faces with or without interfacial mixing. A fibrousfabric may contain one or more laminates. In a spunlaid or meltblownprocess, the fibers are consolidated using industry standard spunbondtype technologies. Typical bonding methods include, but are not limitedto, calender (pressure and heat), thru-air heat, mechanicalentanglement, hydraulic entanglement, needle punching, and chemicalbonding and/or resin bonding. Thermally bondable fibers are required forthe pressurized heat and thru-air heat bonding methods. Fibers may alsobe woven together to form yarns and other fiber products.

The mixture of shaped fibers of the present invention may also be bondedor combined with thermoplastic or non-thermoplastic nonwoven webs orwith film webs to make various articles. The polymeric fibers, typicallysynthetic fibers, or non-thermoplastic polymeric fibers, often naturalfibers, may be used in discrete layers. Suitable synthetic fibersinclude, without limitation, fibers made from polyolefins such aspolyethylene and polypropylene, polyesters such as polyethyleneterephthalate (PET), polyethylene naphthalate (PEN), polytrimethyleneterephthalate (PTT) and polybutylene terephthalate (PBT), polyacticacid, polyurethanes, polycarbonates, polyamides such as Nylon 6, Nylon6,6 and Nylon 6,10, polyacrylates, and copolymers thereof as well asmixtures thereof. Natural fibers include lyocell and cellulosic fibersand derivatives thereof. Suitable cellulosic fibers include thosederived from any tree or vegetation, including hardwood fibers, softwoodfibers, hemp, and cotton. Also included are fibers made from processednatural cellulosic resources such as rayon.

The single layer of shaped fibers of the present invention may beutilized by itself in an article, or the layer may be combined withother nonwoven layers or a film layer to produce a laminate. Examples ofsuitable laminates include, but are not limited tospunbond-meltblown-spunbond laminates. Because of the higher opacity andcontrol over the mechanical properties, a spunbond layer of shapedfibers may have a lower basis weight than a typical spunbond layer madeof only solid round fibers, but still provide the same opacity andmechanical properties as the higher basis weight solid round fiberlayer. Alternatively, a shaped fiber layer may be utilized which enablesthe basis weight or denier of the meltblown layer to be reduced or caneliminate the need for a meltblown layer. A spunbond layer of the shapedfibers of the present invention can also be used in aspundbond-nanofiber-spundbond laminate. The shaped fiber layer can beused as both spunbond layers or only as one spunbond layer. Eachseparate layer in a nonwoven is identified as a layer that is producedwith a different composition of fibers. As described in the presentinvention, a single layer may have a combination of different fibershapes, diameter, configuration, and compositions. The shaped fibernonwoven layer may also be combined with a film web. These laminates areuseful as backsheet and other barriers on disposable nonwoven articles.

The shaped fibers of the present invention may be used to makenonwovens, among other suitable articles. Nonwoven or fibrous fabricarticles are defined as articles that contain greater than 15% of aplurality of fibers that are non-continuous or continuous and physicallyand/or chemically attached to one another. The nonwoven may be combinedwith additional nonwovens or films to produce a layered product usedeither by itself or as a component in a complex combination of othermaterials, such as a baby diaper or feminine care pad. Preferredarticles are disposable, nonwoven articles. The resultant products mayfind use in filters for air, oil and water; vacuum cleaner filters;furnace filters; face masks; coffee filters, tea or coffee bags; thermalinsulation materials and sound insulation materials; nonwovens forone-time use sanitary products such as diapers, feminine pads, andincontinence articles; biodegradable textile fabrics for improvedmoisture absorption and softness of wear such as micro fiber orbreathable fabrics; an electrostatically charged, structured web forcollecting and removing dust; reinforcements and webs for hard grades ofpaper, such as wrapping paper, writing paper, newsprint, corrugatedpaper board, and webs for tissue grades of paper such as toilet paper,paper towel, napkins and facial tissue; medical uses such as barrierproducts, surgical drapes, wound dressing, bandages, dermal patches andself-dissolving sutures; and dental uses such as dental floss andtoothbrush bristles. The fibrous web may also include odor absorbents,termite repellants, insecticides, rodenticides, and the like, forspecific uses. The resultant product absorbs water and oil and may finduse in oil or water spill clean-up, or controlled water retention andrelease for agricultural or horticultural applications. The resultantfibers or fiber webs may also be incorporated into other materials suchas saw dust, wood pulp, plastics, and concrete, to form compositematerials, which can be used as building materials such as walls,support beams, pressed boards, dry walls and backings, and ceilingtiles; other medical uses such as casts, splints, and tongue depressors;and in fireplace logs for decorative and/or burning purpose. Preferredarticles of the present invention include disposable nonwovens forhygiene applications, such as facial cloths or cleansing cloths, andmedical applications. Hygiene applications include wipes, such as babywipes or feminine wipes; diapers, particularly the top sheet, leg cuff,ear, side panel covering, back sheet or outer cover; and feminine padsor products, particularly the top sheet. Other preferred applicationsare wipes or cloths for hard surface cleansing. The wipes may be wet ordry.

CONTINUOUS FIBER EXAMPLES

The Examples below further illustrate the present invention. Apolypropylene was purchased from ATOFINA as FINA 3860X. Twopolypropylenes were purchased from Basell, Profax PH-835 and PDC-1274. Apolyethylene was purchased from Dow Chemical as Aspun 6811A. Twopolyester resins were purchased from Eastman Chemical Company as EastmanF61HC as a PET and Eastman 14285 as a coPET. The meltblown grade resinpolypropylene was purchased from Exxon Chemical Company as Exxon 3456G.

The opacity measurements shown are made on an Opacimeter Model BNL-3Serial Number 7628. Three measurements are made on one specimen with anaverage of three specimens for each material used.

COMPARATIVE EXAMPLES: 100% SOLID ROUND, HOLLOW ROUND OR TRILOBAL

A polypropylene spunbond fabric is produced from Basell PH-835, exceptfor examples C13-15 which are produced from FINA 3860X. C1-C7 andC13-C33 have a through-put per hole of 0.4 ghm. C8-C12 have athrough-put per hole of 0.65 ghm. The shape of the fiber is indicated inthe table as solid round (SR), hollow round (HR) and trilobal (TRI). Allcomparative examples are using 2016 hole spinneret. The fibers areattenuated to an average fiber diameter or denier indicated in the tablebelow. These fibers are thermally bonded together using heat andpressure. The following nonwoven fabrics are produced, basis weightdetermined, and the opacity and/or CD tensile strength of the nonwovenis measured on the samples. TABLE 3 Comparative Opacity Basis FiberFiber Weight Diameter Denier Opacity No. Shape (gsm) (μm) (dpf) (%) C1SR 25 15.3 1.5 25.4 C2 SR 17 15.3 1.5 18.2 C3 SR 10 15.3 1.5 10.5 C4 SR17 14 1.25 18.7 C5 SR 25 14 1.25 26.4 C6 SR 17 12.5 1.0 19.7 C7 SR 1711.2 0.8 20.9 C8 SR 26 14 1.25 26.4 C9 SR 24 14 1.25 23.8 C10 SR 18 141.25 18.5 C11 SR 21 16 1.62 18.5 C12 SR 26 16 1.62 23.8 C13 SR 21 131.07 21.7 C14 SR 18 13 1.07 18.8 C15 SR 17 13 1.07 16.4 C16 HR 25 — 1.2533.3 C17 HR 17 — 1.25 26.0 C18 HR 10 — 1.25 16.3 C19 TRI 25 — 1.25 41.8C20 TRI 17 — 1.25 34.0 C21 TRI 10 — 1.25 21.6

TABLE 4 Comparative Mechanical Properties Maximum CD Basis Fiber TensileWeight Denier Strength No. Shape (gsm) (dpf) (g/in) C22 SR 25 1.5 1370C23 SR 25 1.25 1590 C24 SR 17 1.5 1170 C25 SR 17 1.25 1045 C26 SR 17 0.8950 C27 SR 10 1.5 530 C28 HR 25 1.25 2040 C29 HR 17 1.25 1310 C30 HR 101.25 630 C31 TRI 25 1.25 810 C32 TRI 17 1.25 760 C33 TRI 10 1.25 470

EXAMPLES Example 5 Fibrous Web Containing Mixture of Hollow Round, SolidRound and Trilobal Opacity and Mechanical Properties

A polypropylene spunbond fabric is produced using solid round (SR),hollow round (HR) and trilobal fibers (TRI) made from Basell PH-835. Aspecial spinneret is used that contains a mixture of fiber shapes and ametering plate to feed polymer to each orifice. The through-put perholes is 0.4 ghm using 2016 hole spinneret. The fibers are attenuated toan average fiber diameter or denier indicated in the table. The fibersare thermally bonded together using heat and pressure. The followingnonwoven fabrics are produced, basic weight determined, and the opacityand/or CD tensile strength of the nonwoven is measured on the samples.TABLE 5 Examples of shaped fiber web and opacity and mechanicalproperties Basis Maximum Weight Fiber Ratio Fiber Denier (dpf) OpacityCD Strength (gsm) SR HR TRI SR HR TRI (%) (g/in) 25 80 10 10 1.25 1.251.25 28.6 1560 25 60 20 20 1.25 1.25 1.25 30.9 1520 25 40 30 30 1.251.25 1.25 33.1 1500 25 20 40 40 1.25 1.25 1.25 35.3 1460 25 10 45 451.25 1.25 1.25 36.4 1450 17 80 10 10 1.25 1.25 1.25 21.0 1040 17 60 2020 1.25 1.25 1.25 23.2 1040 17 40 30 30 1.25 1.25 1.25 25.5 1040 17 2040 40 1.25 1.25 1.25 27.7 1040 17 10 45 45 1.25 1.25 1.25 28.9 1040 1080 10 10 1.25 1.25 1.25 11.0 510 10 60 20 20 1.25 1.25 1.25 13.0 520 1040 30 30 1.25 1.25 1.25 15.0 530 10 20 40 40 1.25 1.25 1.25 17.0 540 1010 45 45 1.25 1.25 1.25 18.0 545 25 90 0 10 1.25 — 1.25 27.9 1510 25 500 50 1.25 — 1.25 34.1 1200 25 10 0 90 1.25 — 1.25 40.3 900 17 90 0 101.25 — 1.25 32.5 790 17 50 0 50 1.25 — 1.25 26.4 900 17 10 0 90 1.25 —1.25 20.2 1020 10 90 0 10 1.25 — 1.25 10.3 490 10 50 0 50 1.25 — 1.2515.3 490 10 10 0 90 1.25 — 1.25 20.3 470 25 0 90 10 — 1.25 1.25 34.21920 25 0 50 50 — 1.25 1.25 37.6 1425 25 0 10 90 — 1.25 1.25 41.0 930 170 90 10 — 1.25 1.25 26.8 1255 17 0 50 50 — 1.25 1.25 30.0 1033 17 0 1090 — 1.25 1.25 33.2 815 10 0 90 10 — 1.25 1.25 16.8 610 10 0 50 50 —1.25 1.25 19.0 550 10 0 10 90 — 1.25 1.25 21.1 490 25 90 10 0 1.25 1.25— 27.1 1630 25 50 50 0 1.25 1.25 — 29.9 1815 25 10 90 0 1.25 1.25 — 32.61995 17 90 10 0 1.25 1.25 — 19.4 1070 17 50 50 0 1.25 1.25 — 22.4 118017 10 90 0 1.25 1.25 — 25.3 1280 10 90 10 0 1.25 1.25 —  9.7 510 10 5050 0 1.25 1.25 — 12.7 670 10 10 90 0 1.25 1.25 — 15.6 620

Example 6 Fibrous Webs Containing Two Polymers and Two Shapes

A spunbond machine is set-up to run polypropylene at 220° C. orpolyester at 290° C. A spinneret as shown in FIGS. 9A and 9B may be usedto produce the fibers. A metering system with two melt pumps may be usedto control each polymer type and melt flow. Nonwovens can be produced ata range of mass flow ratios and deniers. Any combination of polymers andshapes may be used. For example, Basell PH-835 solid round fibers may becombined with Dow Aspun 6811A and/or Eastman F61HC trilobal fibers.Alternatively, the Basell PH-835 could be used to make trilobal fibersand hollow round fibers made of ATOFINA 3860X.

Example 7 Fibrous Webs Containing Two Polymers and Two Shapes and aMeltblown Layer

The fibrous fabric of Example 6 is made and combined with apolypropylene meltblown layer made from Exxon 3546G. The averagemeltblown diameter is 3 microns at a through-put of 0.6 ghm. The twolayers can be thermally bonded together or hydroentangled or combinedwith other bonding methods.

Example 8 Fibrous Webs Containing One Polymer and Two Shapes

A fibrous web is produced with solid round meltblown diameter fiberssupplied at 0.15 ghm and trilobal spunlaid diameter fiber supplied at0.4 ghm. In another embodiment, a solid round spunlaid diameter fiber isalso produced in the same layer to create a three-fiber layer.

Example 9 Fibrous Web Containing a Mixture of Multicomponent Solid Roundand Multicomponent Trilobal Fibers

A spunbond nonwoven is produced containing a 50/50 weight percentmixture of multicomponent solid round and multicomponent trilobalfibers. The multicomponent solid round fibers are sheath and core with a50/50 weight percent ratio of ATOFINA 3860X as the sheath material andBasell Profax PH-835 as the core. The solid round fibers are attenuatedto a range of diameters down to 1.0 dpf, depending on the massthroughput per capillary. The trilobal fibers are composed of a 20/80weight percent ratio of ATOFINA as the trilobal tip material and BasellProfax PH-835 as the core. The trilobal fibers are attenuated to a rangeof diameters down to 1.0 dpf, depending on the mass throughput percapillary. These fibers are then consolidated together usingconventional bonding methods, most commonly thermal point bonding, buthydroentangling can also be used. Basis weight down to 5 gsm can beproduced. If desired, a polypropylene meltblown layer can be producedusing Exxon 3546G. The average meltblown diameter is 3 microns at athrough-put of 0.6 ghm. The meltblown layer is then combined with thespunlaid layer either by direct collection or brought in from a secondsource. Other alternate layers can be added. The fibers are thermallybonded together using heat and pressure. This nonwoven has high opacitycharacteristics with improved strength due to the presence of the lowermolecular weight ATOFINA 3860X outer component of the multicomponentfibers. The component ratio of individual fibers can be changed tofurther adjust the strength and the ratio of shaped fibers can bechanged to alter the opacity and strength, as needed for a desiredapplication.

Example 10 Fibrous Web Containing a Mixture of Multicomponent SolidRound and Multicomponent Trilobal Fibers Plus Mixed Meltblown Diameter

A spunbond nonwoven is produced containing a 45/45/10 weight percentmixture of multicomponent solid round, multicomponent trilobal fibers,and meltblown diameter fibers. The multicomponent solid round fibers aresheath and core with a 50/50 weight percent ratio of ATOFINA 3860X asthe sheath material and Basell Profax PH-835 as the core. The solidround fibers are attenuated to a range of diameters down to 1.0 dpf,depending on the mass throughput per capillary. The trilobal fibers arecomposed of a 20/80 weight percent ratio of ATOFINA as the trilobal tipmaterial and Basell Profax PH-835 as the core. The trilobal fibers areattenuated to a range of diameters down to 1.0 dpf, depending on themass throughput per capillary. The solid round and trilobal spunbondorifice are supplied a polymer at 0.4 ghm, while the meltblown diameterorifices are supplied polymer at 0.15 ghm. All of these fibers areextruded from an etched metering plate and spinneret. The meltblowndiameter fibers have an average diameter of 6 microns. These fibers arethen consolidated together using conventional bonding methods. Thisnonwoven also has high opacity characteristics with improved strengthdue to the presence of the lower molecular weight ATOFINA 3860X outercomponent of the multicomponent fibers. The component ratio inindividual fibers can be changed to further adjust the strength and theratio of shaped fibers can be changed to alter the opacity and strength,as needed for a desired application.

Example 11 Fibrous Web Containing a Mixture of Multicomponent SolidRound, Monocomponent Trilobal Fibers and Meltblown Diameter Fibers

A spunbond nonwoven is produced containing a 20/70/10 weight percentmixture of multicomponent solid round, monocomponent trilobal fibers andmeltblown diameter fibers. The multicomponent solid round fibers are a75/25 weight percent ratio of Eastman F61HC polyester as the corematerial and Eastman 14285 as the sheath material. The multicomponentround fibers are attenuated to a range of diameters down to 1.0 dpf,depending on the mass throughput per capillary. The monocomponenttrilobal fibers are composed of Eastman F61HC. The polyester meltblownfibers are produced using an Eastman F33HC. The monocomponent trilobalfibers are attenuated to a range of sizes down to 1.0 dpf, depending onthe mass throughput per capillary. The average meltblown diameter is 3microns at a through-put of 0.6 ghm. This construction is used toproduce a high strength and loft polyester spunbond. The component ratioin individual fibers and between fiber types can be changed to furtheralter the opacity and strength, as needed for a desired application.

Example 12 Fibrous Web Containing a Mixture of Multicomponent SolidRound and Monocomponent Trilobal Fibers

A spunbond nonwoven is produced containing a 20/70/10 weight percentmixture of multicomponent solid round, monocomponent trilobal fibers andmeltblown diameter fibers from the same spinneret. Alternatively, aspunbond nonwoven can be produced containing a 30/70 weight percentmixture of multicomponent solid round and monocomponent trilobal fibers.The multicomponent solid round fibers are a 75/25 weight percent ratioof Eastman F61HC polyester as the core material and Eastman 14285 as thesheath material. The multicomponent round fibers are attenuated to arange of diameters down to 1.0 dpf, depending on the mass throughput percapillary. The monocomponent trilobal fibers are composed of Eastman F61HC. If present, the polyester meltblown fibers are produced using anEastman F33HC. The monocomponent trilobal fibers are attenuated to arange of sizes down to 1.0 dpf, depending on the mass throughput percapillary. The average meltblown diameter is 6 microns at a through-putof 0.15 ghm. The nonwoven web with shaped fibers may be combined with ameltblown layer. Other alternate layers can be added.

Many examples have been shown and given here to demonstrate the variousequipment embodiments, methods of forming mixed fiber products havingdifferent geometries and the breadth of fibers that can be produced toillustrate the invention. Although not limited by the data presented inthis invention, further variations are known.

The disclosures of all patents, patent applications (and any patentswhich issue thereon, as well as any corresponding published foreignpatent applications), and publications mentioned throughout thisdescription are hereby incorporated by reference herein. It is expresslynot admitted, however, that any of the documents incorporated byreference herein teach or disclose the present invention.

While particular embodiments of the present invention have beenillustrated and described, it would be obvious to those skilled in theart that various other changes and modifications can be made withoutdeparting from the spirit and scope of the invention. It is intended tocover in the appended claims all such changes and modifications that arewithin the scope of the invention.

1. A spinneret comprising at least two spinneret orifices havinggeometries different from each other.
 2. The spinneret of claim 1,wherein at least one spinneret orifice has a geometry that is configuredto form a hollow fiber.
 3. The spinneret of claim 1, wherein thegeometries of the spinneret orifices include round and multi-lobal. 4.The spinneret of claim 3, wherein the geometries of the spinneretorifices include trilobal.
 5. The spinneret of claim 3, wherein at leastsome of the round spinneret orifices are located closer to peripheralportions of the spinneret in relation to all multi-lobal spinneretorifices.
 6. The spinneret of claim 3, wherein only round spinneretorifices are located within a selected section disposed at eachlongitudinal end portion of the spinneret.
 7. The spinneret of claim 3,wherein only round spinneret orifices are located within a centralportion of the spinneret.
 8. The spinneret of claim 1, wherein at leastone group of the multi-lobal spinneret orifices are formed along anoutlet surface the spinneret such that a lobe of a multi-lobal fiberextruded from each multi-lobal spinneret orifice of the at least onegroup is aligned to face in a direction of a quench medium source thatdirects a quench medium toward fibers extruded from the spinneret. 9.The spinneret of claim 1, wherein the spinneret includes a first groupof multi-lobal spinneret orifices and a second group of multi-lobalspinneret orifices that have the same geometric shape as the first groupof multi-lobal spinneret orifices, the multi-lobal orifices of the firstgroup being aligned along an outlet surface of the spinneret at aselected angle of rotation with respect to the multi-lobal spinneretorifices of the second group.
 10. The spinneret of claim 9, wherein themulti-lobal spinneret orifices of the first group are aligned at a 180°rotation with respect to the multi-lobal spinneret orifices of thesecond group.
 11. The spinneret of claim 1, wherein at least 50% of thespinneret orifices have a multi-lobal geometry.
 12. The spinneret ofclaim 1, wherein at least 75% of the spinneret orifices have amulti-lobal geometry.
 13. The spinneret of claim 1, wherein at least 80%of the spinneret orifices have a multi-lobal geometry.
 14. Ametering/distribution plate for use in a spin pack assembly thatcomprises a spinneret including a first set of spinneret orifices and asecond set of spinneret orifices, the spinneret orifices of the firstset having geometries that are different from geometries of thespinneret orifices of the second set, the metering/distribution platecomprising: a first set of passages configured to deliver molten polymerflowing through the spin pack assembly to the first set of spinneretorifices; and a second set of passages configured to deliver moltenpolymer flowing through the spin pack assembly to the second set ofspinneret orifices; wherein the passages for each set are selected tofacilitate the formation of extruded fibers through the first and secondsets of spinneret orifices having selected deniers.
 15. Themetering/distribution plate of claim 14, wherein the passages of theplate are vertical through-holes that have been drilled in the plate.16. The metering/distribution plate of claim 14, wherein the passages ofthe plate include horizontally formed channels disposed along a firstsurface of the plate and vertical through-holes in fluid communicationwith the channels and extending to a second surface of the plate. 17.The metering/distribution plate of claim 16, wherein the channels have achannel width to a channel depth ratio of about 1.5:1 to about 15:1. 18.A spin pack assembly comprising: a spinneret comprising a first set ofspinneret orifices and a second set of spinneret orifices, the spinneretorifices of the first set having geometries different from geometries ofthe spinneret orifices of the second set; and a metering/distributionplate configured to deliver molten polymer flowing through the spin packassembly to the spinneret, the metering/distribution plate comprising aa first set of passages configured to deliver molten polymer flowingthrough the spin pack assembly to the first set of spinneret orifices,and a second set of passages configured to deliver molten polymerflowing through the spin pack assembly to the second set of spinneretorifices, wherein the passages for each set are selected to facilitatethe formation of extruded fibers through the first and second sets ofspinneret orifices having selected deniers.
 19. The spin pack assemblyof claim 18, wherein the geometries of the spinneret orifices includeround and multi-lobal.
 20. The spin pack assembly of claim 18, whereinthe spin pack assembly is configured to receive differentmetering/distribution plates including different sets of passages havingdifferent passage dimensions.
 21. A method of forming a mixed filamentproduct including polymer fibers with different cross-sectionalgeometries, the method comprising: providing a spin pack assemblyincluding a spinneret with a first set of spinneret orifices and asecond set of spinneret orifices, the spinneret orifices of the firstset having geometries that are different from geometries of thespinneret orifices of the second set.
 22. The method of claim 21,wherein the geometries of the spinneret orifices include round andmulti-lobal.
 23. The method of claim 22, wherein at least one group ofthe multi-lobal spinneret orifices are formed in the spinneret such thata lobe of a multi-lobal fiber extruded from each multi-lobal spinneretorifice of the at least one group is aligned to face in a direction of aquench medium source that directs a quench medium toward fibers extrudedfrom the spinneret.
 24. The method of claim 21, further comprising:providing a metering/distribution plate for the spin pack assembly, themetering/distribution plate being configured to deliver molten polymerflowing through the spin pack assembly to the spinneret and including afirst set of passages configured to deliver molten polymer flowingthrough the spin pack assembly to the first set of spinneret orifices,and a second set of passages configured to deliver molten polymerflowing through the spin pack assembly to the second set of spinneretorifices.
 25. The method of claim 24, further comprising: providing thepassages of the first set of the metering/distribution plate withselected dimensions to control the deniers of fibers extruded from thefirst set of spinneret orifices; and providing the passages of thesecond set of the metering/distribution plate with selected dimensionsto control the deniers of fibers extruded from the second set ofspinneret orifices.
 26. The method of claim 24, further comprising:modifying at least one operating parameter selected from: polymerthroughput through the spin pack assembly, fiber cross-sectionalgeometry of fibers formed from the spinneret, the arrangement ofspinneret orifices along the spinneret, a temperature of polymermaterial flowing through the spin pack assembly, denier of fibers formedfrom at least one of the first and second sets of spinneret orifices,the number of spinneret orifices in at least one of the first and secondsets of spinneret orifices, and polymer material of fibers extruded fromthe spinneret; and replacing the metering/distribution plate in the spinpack assembly with a different metering/distribution plate includingselected passage dimensions to facilitate selective control of thedeniers of fibers extruded from the spinneret after the modification ofthe at least one operating parameter.
 27. The method of claim 21,wherein fibers formed from the spinneret include at least one of: fibershaving different cross-sectional geometries but with the same one ormore polymer components, and fibers having different cross-sectionalgeometries and different polymer components.
 28. The method of claim 21,wherein at least some of the fibers formed from the spinneret includemulti-polymer components.
 29. A spunlaid system comprising: a spin packassembly comprising: a spinneret comprising a first set of spinneretorifices and a second set of spinneret orifices, the spinneret orificesof the first set having geometries different from geometries of thespinneret orifices of the second set; and a metering/distribution plateconfigured to deliver molten polymer flowing through the spin packassembly to the spinneret, the metering/distribution plate comprising aa first set of passages configured to deliver molten polymer flowingthrough the spin pack assembly to the first set of spinneret orifices,and a second set of passages configured to deliver molten polymerflowing through the spin pack assembly to the second set of spinneretorifices, wherein the channels for each set are selected to facilitatethe formation of extruded fibers through the first and second sets ofspinneret orifices having selected deniers; and a quench source alignedand configured to direct at least one source of quench medium towardfibers extruded from the spinneret.
 30. The system of claim 29, whereinat least one group of the multi-lobal spinneret orifices are formedalong an outlet surface the spinneret such that a lobe of a multi-lobalfiber extruded from each multi-lobal spinneret orifice of the at leastone group is aligned to face in a direction of a quench medium sourcethat directs a quench medium toward fibers extruded from the spinneret.31. The system of claim 29, further comprising: a plurality of meteringpumps to independently meter molten polymer material to the spin packassembly.
 32. The system of claim 31, wherein a first metering pumpmeters a molten polymer material to the first set of passages of themetering/distribution plate, and a second metering pump meters moltenpolymer material to the second set of passages of themetering/distribution plate.